Sensorimotor control of functional joint stability: Scientific concepts, clinical considerations, and the articuloneuromuscular cascade paradigm in peripheral joint injury

Human movement depends on sensorimotor control. Sensorimotor control refers to central nervous system (CNS) control of joint stability, posture, and movement, all of which are effected via the sensorimotor system. Given the nervous, muscular, and skeletal systems function as an integrated "neuromusculoskeletal system" for the purpose of executing movement, musculoskeletal conditions can result in a cascade of impairments that affect negatively all three systems. The purpose of this article is to revisit concepts in joint stability, sensorimotor control of functional joint stability (FJS), joint instability, and sensorimotor impairments contributing to functional joint instability. This article differs from historical work because it updates previous models of joint injury and joint instability by incorporating more recent research on CNS factors, skeletal muscle factors, and tendon factors. The new 'articuloneuromuscular cascade paradigm' presented here offers a framework for facilitating further investigation into physiological and biomechanical consequences of joint injury and, in turn, how these follow on to affect physical activity (functional) capability. Here, the term 'injury' represents traumatic joint injury with a focus is on peripheral joint injury. Understanding the configuration of the sensorimotor system and the cascade of post-injury sensorimotor impairments is particularly important for clinicians reasoning rational interventions for patients with mechanical instability and functional instability. Concurrently, neurocognitive processing and neurocognitive performance are also addressed relative to feedforward neuromuscular control of FJS. This article offers itself as an educational resource and scientific asset to contribute to the ongoing research and applied practice journey for developing optimal peripheral joint injury rehabilitation strategies.

A Rehabilitation Algorithm After Lateral Ankle Sprains in Professional Football (Soccer): An Approach Based on Clinical Practice Guidelines

Lateral ankle sprain (LAS) is one of the most common types of injury in professional football (soccer) players with high risk of recurrence. The rehabilitation after LAS in professional football players is often still time-based and relies on anecdotal experience of clinicans. There is still a lack of utilization of criteria-based rehabilitation concepts after LAS in professional football. The aims of this clinical commentary are (1) to critically discuss the need for criteria-based rehabilitation concepts after LAS in professional football players, (2) to highlight the current lack of these approaches and (3) to present a novel clinical guideline-based rehabilitation algorithm. Short time-loss (15 days) and high recurrence rate (17%) raise the question of trivialization of LAS in professional football. Despite consequences for many stakeholders involved (players, teams, clubs, insurers), there is still a lack of of criteria-based, step-by-step approaches. The use of a criteria-based rehabilitation approach might reduce the high recurrence rate after LAS in professional football players and will lead, in turn, to increased long-term player availability. Practical experiences of he authors demonstrate the feasibility of such an approach. The effectiveness of this novel rehabilitation algorithm remains to be evaluated in future studies. Level of Evidence: 5.

The Nature of Rehabilitation Programs to Improve Musculoskeletal, Biomechanical, Functional, and Patient-Reported Outcomes in Athletes With ACL Reconstruction: A Scoping Review

CONTEXT

After anterior cruciate ligament (ACL) reconstruction (ACLR), athletes commonly undergo prolonged rehabilitation (eg, 9-12 months), but few actually return to preinjury sports activities. The nature (composition, configuration) of an ACL rehabilitation program (ACL-RP) is an important factor in determining rehabilitation outcomes; however, details about the nature of ACL-RPs are reported inconsistently in research studies. To guide future research reporting to support clinical translation and implementation of ACL-RPs, it is necessary to describe the nature, reporting, and outcomes of ACL-RPs in the current literature.

OBJECTIVE

The purpose of this scoping review was to understand the nature and reporting of various ACL-RPs that address musculoskeletal, biomechanical, functional, or patient-reported outcome measures in adult and pediatric athletes with ACLR.

DATA SOURCES

Articles were selected from searches in 5 electronic databases (PubMed, EbscoHost [MEDLINE, SportDiscus, CINAHL Plus], PROQuest, Cochrane, and Embase).

STUDY SELECTION

Studies were included if they evaluated a post-ACL-RP that implemented strength, balance, plyometric, change of direction running, and/or agility running and included self-reported physical function, quality of life, or pain outcomes.

STUDY DESIGN

Scoping review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR) guidelines.

LEVEL OF EVIDENCE

Level 4.

DATA EXTRACTION

Data were extracted and synthesized to evaluate the reporting of acute program variables (APVs) and exercise descriptors (EDs); 17 studies were included in the final synthesis.

RESULTS

Studies reported between 0% and 67% of the APVs and EDs combined. Only 2 studies were considered to have adequate reporting of both APVs and EDs.

CONCLUSION

Inadequate reporting of APVs and EDs in past studies restricts the translation and implementation of existing research-based ACL-RPs to present-day clinical contexts.

A New Way to Restrict Free Leg Movement During Unilateral Vertical Jump Test

The purpose of this investigation was (1) to test the effect of movement restriction of the free leg during unilateral vertical jump on performance and power output comparing 2 different jump techniques: flexed (Classic technique) and straight (FC Luzern technique) free leg, and (2) to test the correlation between performance and power output obtained using these 2 techniques. Twenty elite soccer players performed squat (SJ) and countermovement (CMJ) jumps on each leg. The jump height and peak power output were compared between the 2 techniques for both legs. The jump height and peak power were significantly higher for the classic test for SJ and CMJ (P < .001) with no side effects or interactions. The angular range of motion of the free leg was higher for the Classic test than for the FC Lucerne test (P < .001), with no difference in the angular range of motion of the trunk. A moderate correlation was found between the 2 techniques on peak power (SJ: r = .626; CMJ: r = .649) and jump height (SJ: r = .742; CMJ: r = .891). Consequently, FC Lucerne technique, limiting the contribution of the free leg, is more appropriate to assess lower limb strength capacities during unilateral jump test.

Association between single leg hop tests and patient reported outcome measures and patellar instability in patients with recurrent patellar dislocations

Objectives

To assess the associations between the single leg hop tests at two premises; baseline and the change after 12 months, and change in patient reported outcome measures and persistent instability after 12 months in patients with recurrent lateral patellar dislocation (RLPD).

Methods

61 RLPD patients aged 12-30 with a mean (±SD) of 19.2 (±5.3) were assessed at baseline, and at 12 months after treatment with either active rehabilitation alone, or medial patellofemoral ligament reconstruction and active rehabilitation. Single leg hop for distance, triple hop for distance, crossover hop for distance and 6-metre timed hop were performed for both legs, and the Limb Symmetry Index (LSI) was calculated. Persistent patellar instability was self-reported as 'Yes' or 'No' at 12-month follow-up. Knee function in sport and recreational activities and knee-related quality of life were assessed at baseline and 12 months follow-up using the Knee injury and Osteoarthritis Outcome Score (KOOS).

Results

LSI for the baseline single leg hop for distance and the triple hop for distance was significantly associated with persistent patellar instability at 12 months follow-up with an OR of 0.94 (95% CI 0.88 to 0.99) and OR of 0.91 (95% CI 0.84 to 0.99), respectively. No other statistically significant associations were detected.

Conclusion

Individuals with higher LSI values for the single leg hop for distance and triple hop for distance conducted at baseline had lower odds for persistent patellar instability at 12 months follow-up. Clinicians can use results from these hop tests to assess the risk of future recurrent patellar instability prior to treatment.

Study design

Retrospective cohort study.

Trial registration number

NCT02263807.

Test-retest reliability of quantitative sensory testing, active joint position sense, and functional hop testing in amateur adult athletes with unilateral anterior cruciate ligament reconstruction

OBJECTIVES

The somatosensory system fulfils a critical role in functional knee joint stability (FKJS) by providing afferent feedback necessary for neuromuscular control. Individuals with anterior cruciate ligament reconstruction (ACLr) have altered somatosensory function. Somatosensory characteristics are assessed by proprioception and quantitative sensory testing. The purpose of the study was to examine intra-rater and inter-rater reliability of methods used to assess somatosensory characteristics and FKJS in amateur adult athletes with unilateral ACLr.

DESIGN

Repeated measures.

SETTING

University.

PARTICIPANTS

8 female, 4 male with unilateral autogenous ACLr.

MAIN OUTCOME MEASURES

Bilateral measurements at 5 lower extremity locations and the anterior forearm: light touch (LT), vibration sense (VS), pressure pain threshold (PPT); knee active joint position sense (AJPS); adapted crossover hop for distance (ACHD). Intraclass correlation coefficients (ICC) determined reliability, defined as: poor (<0.50), moderate (0.50-0.75), good (0.75-0.90).

RESULTS

ACLr-side intra-rater/inter-rater ICCs ranged: LT, -0.27-0.80/-0.01-0.84; VS, 0.12-0.90/0.25-0.90; PPT, 0.49-0.98/0.86-0.99; AJPS, 0.15-0.79/0.55-0.87; ACHD, 0.98/0.99. Uninjured-side intra-rater/inter-rater ICCs ranged: LT, 0.12-0.66/-0.09-0.64; VS, 0.35-0.89/0.05-0.81; PPT, 0.65-0.99/0.45-0.95; AJPS, 0.07-0.81/0.37-0.99; ACHD, 0.99/0.98.

CONCLUSIONS

Intra-rater and inter-rater reliability was poor to good for both limbs. Overall, PPT and the ACHD demonstrated the highest ICCs. Some somatosensory assessments can be employed with confidence, while others should be used with caution.

Hop to It! The Relationship Between Hop Tests and The Anterior Cruciate Ligament - Return to Sport Index After Anterior Cruciate Ligament Reconstruction in NCAA Division 1 Collegiate Athletes

Background

Outcomes after anterior cruciate ligament reconstruction (ACLR) may not be optimal, with poor physical and psychological function potentially affecting return to sport (RTS) ability. Understanding the relationship between commonly used hop tests and the Anterior Cruciate Ligament - Return to Sport Index (ACL-RSI) may improve rehabilitation strategies and optimize patient outcomes.

Hypothesis/Purpose

The purpose of this study was to examine the relationship between ACL-RSI scores and limb symmetry index (LSI) for the single hop for distance (SHD), triple hop for distance (THD), crossover hop for distance (CHD), timed 6-meter hop (T6H), and single leg vertical hop (SLVH) in a cohort of National Collegiate Athletic Association (NCAA) Division 1 collegiate athletes after ACLR. The hypothesis was that SLVH LSI would be more highly correlated with ACL-RSI score than all horizontal hop tests.

Study design

Cross-Sectional Study.

Methods

Twenty-one National Collegiate Athletic Association (NCAA) Division 1 collegiate athletes (7 males, 14 females) at 6.62 ± 1.69 months after ACLR were included in this retrospective study. Primary outcomes were ACL-RSI score and LSI for SHD, THD, CHD, T6H, and SLVH. The relationship between ACL-RSI scores and performance on hop tests (LSIs) was evaluated using correlation analysis and step-wise linear regression (p ≤ 0.05).

Results

There were significant correlations found when comparing ACL-RSI and the LSI for SHD (rs = 0.704, p < 0.001), THD (rs = 0.617, p = 0.003), CHD (rs = 0.580, p = 0.006), and SLVH (rs = 0.582, p = 0.006). The CHD explained 66% (R2 value of 0.660) of the variance in the ACL-RSI, while the other hop tests did not add to the predictive model.

Conclusions

Physical function has the capacity to influence psychological status after ACLR. Clinicians should recognize that SLVH, SHD, THD, and CHD are correlated with ACL-RSI and improvements in physical function during rehabilitation may improve psychological status and optimize RTS after ACLR.

Level of evidence

Level 3.

Evaluation of the Back-in-Action test Battery In Uninjured High School American Football Players

Background

Return to sport testing is an established routine, especially for athletes who have ruptured their anterior cruciate ligament (ACL). Various tests are performed, often combined in test batteries, such as the Back-in-action (BIA) test battery. Unfortunately, pre-injury performance is often unknown, and only few athletes pass the high demands of these test batteries.

Purpose

The aim of the study was to determine the performance of under 18 American football players on the BIA to establish pre-injury sport specific benchmarks for future RTS testing and to compare these values to data from an age-matched reference group.

Methods

Fifty-three healthy male American football players underwent a functional assessment using the "Back-in-action" test battery evaluating agility, speed (Parkour-Jumps and Quick-Feet test), balance (using a PC based balance board), and power (Counter-Movement-Jump [CMJ]) as objective measures. Their results were compared with a previously tested reference group (RP) and within the american football players (AF) through three subgroups according to field playing position.

Results

Overall, the American football (AF) athletes showed lower balance scores for both legs (AF: 3.71/3.57/3.61; RP: 3.4/3.2/3.2; p<0.002) compared to the reference population (RP). CMJ height and Quick-Feet results were not statistically different (p>0.05), Parkour-Jump times (AF: 8.18/ 8.13 sec.; RP: 5.9/5.9sec.; p<0.001) were significantly slower. Power output in all CMJ's (AF: 46.86/36.94/37.36 W/kg; RP: 43.2/29.5/29 W/kg; p<0.001) was significantly higher than the RP. Passing and running game involved players (G2 & G3) showed significantly better balance scores (G2+G3: 3.36/3.27/3.33; G1: 4.22/4.06/4.10; p<0.001), higher jump height (G2&G3: 38.87/24.02/24.96 cm; G1: 32.03/19.50/18.96 cm; p<0.001) and more watts/kg (G2&G3: 48.83/37.21/37.64 W/kg; G1: 43.95/36.88/36.53 W/kg; p<0.001) compared to blocking players like Linemen (G1) and to the age matched reference population (RP).

Conclusion

Only 53% of the healthy athletes would have been cleared for sport using the BIA test criteria, which highlights the challenging passing criteria. Despite significantly greater power measurements, scores of balance and agility were poorer compared to the reference group, especially for linemen. These data may serve as sport and position specific reference for high school American football players, instead of using the non-specific reference group data.

Study design

cross-sectional study.

Level of evidence

IIb.

Fatigue does not increase limb asymmetry or induce proximal joint power shift in habitual, multi-speed runners

During prolonged jogging, joint moment and work tend to decrease in the distal (ankle) joint but increase at proximal (hip/knee) joints as performance fatigue manifests, and such adaptations might be expected to occur in sprinting. Fatigue is also thought to increase inter-limb asymmetries, which is speculated to influence injury risk. However, the effects of fatigue on sprint running gait have been incompletely studied, so these hypotheses remain untested. Using statistical parametric mapping, we compared 3-D kinematics and ground reaction force production between the dominant (DL) and non-dominant (NDL) legs of 13 soccer players during both non-fatigued and fatigued sprint running. Contrary to the tested hypotheses, relative between-leg differences were greater in non-fatigued than fatigued sprinting. DL generated higher propulsive impulse due to increased ankle work, while NDL exhibited greater vertical impulse, potentially due to greater hip flexion prior to downward foot acceleration. Whilst few changes were detected in DL once fatigued, NDL shifted towards greater horizontal force production, largely resulting from an increase in plantar flexion (distal-joint) moments and power. After fatiguing running, inter-limb asymmetry was reduced and no distal-to-proximal shift in joint work was detected. These adaptations may attenuate decreases in running speed whilst minimising injury risk.

Dynamic balance and explosive strength appears to better explain single leg hop test results among young elite female basketball athletes

To analyze the impact of balance, lower-limb explosive strength and anthropometric variables on the result of the hop test in young elite female basketball athletes. Ninety young elite female basketball athletes (13-17 years), without current or recent lower-limb injury, were assessed in the off-season period of July 2021. Single leg hop test, countermovement jump, Y balance test and anthropometric outcomes were assessed. A correlation study and a regression model were performed to investigate the influence of such outcomes and the value of their participation on the hop test results. It was found a low-to-moderate correlation effect size for both countermovement jump (distance and power flight) and Y balance test values (except interlimb outcomes) with the single leg hop test results. Anthropometric outcomes did not show significant correlation (p > 0.05). Regression model revealed that for right hop test, countermovement jump values exhibited an adjusted determination coefficient of 0.408, (β = 0.249, p = 0.013), For left hop test, again the countermovement jump values (β = 0.229, p = 0.025), and left Y balance test values (β = 0.331, p = 0.011) jointly obtained an adjusted determination coefficient of 0.263 significant predictive value for countermovement jump outcomes in both right (β = 0.249, p = 0.013; β = 0.301; p = 0.031) and left leg (β = 0.229, p = 0.025; β = 0.365, p = 0.040), as well as certain Y balance outcomes values. Explosive strength, and dynamic balance although to a lesser extent, appear to be the most relevant physical-functional factors influencing the single leg hop test results among young elite female basketball athletes. These findings may a serve as a basis to implement targeted interventions, such as plyometric and balance training, for an enhancement on functional rehabilitation and reducing the risk of injury related to the hop test results.

The Relationship between Lower Extremity Functional Performance and Balance after Anterior Cruciate Ligament Reconstruction: Results of Patients Treated with the Modified All-Inside Technique

BACKGROUND AND OBJECTIVES

Anterior cruciate ligament (ACL) ruptures are common injuries, and ACL reconstruction (ACLR) is among the most common surgical procedures in sports surgery. Our research aims to compare the 6-month post-operative results of the modified all-inside (MAI) ACLR technique, single leg hop tests (SLHT), and Y balance tests applied in different directions on the operated and non-operated sides.

MATERIALS AND METHODS

A retrospective cohort of 22 male recreational athletes who underwent MAI ACLR techniques performed by the same surgeon were evaluated. The functional knee strengths of the participants on the operated and non-operated sides were evaluated with five different tests of SLHTs: single hop for distance (SH), triple hop for distance (TH), crossover triple hop for distance (CH), medial side triple hop for distance (MSTH), and medial rotation (90°) with hop for distance (MRH). Their dynamic balance was evaluated with the Y balance Test.

RESULTS

Compared to pre-operative levels, there was a significant improvement in the mean Lysholm, Tegner, and IKDC scores during the post-operative period (p < 0.05). There was a difference between SH, THD, CHD, MSTH, and MRH on the operated and non-operative sides (p < 0.05). There was no difference between Y balance scores on the operated and non-operative sides, and there were no differences between LSI scores resulting from SLHTs (p > 0.05). There were no significant relationships between YBT (composite scores) and SH, TH, CH, MSTH, and MRH distances in the healthy leg (p > 0.05), but a significant correlation with only CH in the ACL leg (p < 0.05).

CONCLUSIONS

Our research shows that sixth-month post-operative SLHT findings were lower on the ACL side compared to the healthy side in patients tested with the MAI ACLR technique. However, when these scores are evaluated in terms of balance, it can be seen that both sides reveal similar findings. The similarity of LSIs in SLHTs applied in different directions, and balance scores of ACL and healthy sides revealed that the MAI technique is also an ACLR technique that can be used in athletes from a functional point of view.

Patellofemoral Angle, Pelvis Diameter, Foot Posture Index, and Single Leg Hop in Post-Operative ACL Reconstruction

Background and Objectives: Anterior cruciate ligament (ACL) injuries occur as a result of the deterioration of the static and dynamic stability of the knee. One of the structures involved in providing static stability is the patellofemoral angle (Q angle). The aim of this study was to investigate the relationships between Q angle, pelvis diameter, lower extremity length, and foot posture index (FPI) in patients who had undergone ACL reconstruction (ACLR) with the semitendinosus/gracilis (ST/G) technique on both the operated and non-operated sides. Materials and Methods: Twenty-five male recreational athletic patients between the ages of 18 and 35 who had undergone semitendinosus/gracilis (ST/G) anterior cruciate ligament reconstruction at least 6 months earlier were included in the study. Femur length, lower extremity length, pelvis diameter, and Q angle measurements, total foot posture index (FPI) scores, and single leg hop (SLH) and triple hop distance (THD) test results were determined on the operated and non-operated sides. Results: When the findings of the patients were evaluated statistically between the operated and non-operated sides, no significant differences were found in Q angle, femur length, and lower extremity length (p > 0.05). In terms of FPI scores, a significant difference was found only in the inversion/eversion of the calcaneus (CALC) parameter (p < 0.05). When the single hop test (SLHT) results were evaluated statistically on the operated and non-operated sides, the results were in favor of the non-operated side (p < 0.05). In the correlation analysis conducted for both the operated and non-operated sides, positive and significant correlations were found only between SLH and THD (p < 0.05). No significant difference was found in the other parameters. Conclusions: The fact that ST/G ACLR 6th month post-operative findings revealed similar results in Q angle, lower extremity length, and total FPI scores between the operated and non-operated sides showed that the 6-month process did not cause a difference in these parameters. However, it was found that the operated sides showed lower findings compared to non-operated sides for SLHTs, although these findings were within normal ranges in terms of the limb symmetry index.

What tests should be used to assess functional performance in youth and young adults following anterior cruciate ligament or meniscal injury? A systematic review of measurement properties for the OPTIKNEE consensus

OBJECTIVES

To critically appraise and summarise measurement properties of functional performance tests in individuals following anterior cruciate ligament (ACL) or meniscal injury.

DESIGN

Systematic review.

DATA SOURCES

Systematic searches were performed in Medline (Ovid), Embase (Ovid), CINAHL (EBSCO) and SPORTSDiscus (EBSCO) on 7 July 2021.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies evaluating at least one measurement property of a functional performance test including individuals following an ACL tear or meniscal injury with a mean injury age of ≤30 years. The COnsensus-based Standards for the selection of health Measurement INstruments Risk of Bias checklist was used to assess methodological quality. A modified Grading of Recommendations Assessment, Development and Evaluation assessed evidence quality.

RESULTS

Thirty studies evaluating 26 functional performance tests following ACL injury were included. No studies were found in individuals with an isolated meniscal injury. Included studies evaluated reliability (n=5), measurement error (n=3), construct validity (n=26), structural validity (n=1) and responsiveness (n=1). The Single Leg Hop and Crossover Hop tests showed sufficient intrarater reliability (high and moderate quality evidence, respectively), construct validity (low-quality and moderate-quality evidence, respectively) and responsiveness (low-quality evidence).

CONCLUSION

Frequently used functional performance tests for individuals with ACL or meniscal injury lack evidence supporting their measurement properties. The Single Leg Hop and Crossover Hop are currently the most promising tests following ACL injury. High-quality studies are required to facilitate stronger recommendations of performance-based outcomes following ACL or meniscal injury.

Thigh muscle co-contraction patterns in individuals with anterior cruciate ligament reconstruction, athletes and controls during a novel double-hop test

Efficient neuromuscular coordination of the thigh muscles is crucial in maintaining dynamic knee stability and thus reducing anterior cruciate ligament (ACL) injury/re-injury risk. This cross-sectional study measured electromyographic (EMG) thigh muscle co-contraction patterns during a novel one-leg double-hop test among individuals with ACL reconstruction (ACLR; n = 34), elite athletes (n = 22) and controls (n = 24). Participants performed a forward hop followed by a 45° unanticipated diagonal hop either in a medial (UMDH) or lateral direction (ULDH). Medial and lateral quadriceps and hamstrings EMG were recorded for one leg (injured/non-dominant). Quadriceps-to-Hamstring (Q:H) ratio, lateral and medial Q:H co-contraction indices (CCIs), and medial-to-lateral Q:H co-contraction ratio (CCR; a ratio of CCIs) were calculated for three phases (100 ms prior to landing, initial contact [IC] and deceleration phases) of landing. We found greater activity of the quadriceps than the hamstrings during the IC and deceleration phases of UMDH/ULDH across groups. However, higher co-contraction of medial rather than lateral thigh muscles during the deceleration phase of landing was found; if such co-contraction patterns cause knee adduction, a putative mechanism to decrease ACL injury risk, during the deceleration phase of landing across groups warrants further investigation.

Variability and Complexity of Knee Neuromuscular Control during an Isometric Task in Uninjured Physically Active Adults: A Secondary Analysis Exploring Right/Left and Dominant/Nondominant Asymmetry

Work is needed to better understand the control of knee movement and knee health. Specifically, work is needed to further understand knee muscle force control variability and complexity and how it is organized on both sides of the body. The purpose of this study was to explore side-to-side comparisons of magnitude- and complexity-based measures of knee muscle force control to support future interpretations of complexity-based analyses and clinical reasoning in knee injury control. Participants (male/female n = 11/5) performed constant-force isometric efforts at 50% maximal effort. Force variability was quantified during the constant-force efforts using a coefficient of variation (CV%) and force complexity using approximate entropy (ApEn) and detrended fluctuation analysis (DFA) α. Outcomes were right/left and dominant/nondominant group-level and individual-level comparisons. A limb-symmetry index was calculated for each variable and clinically significant absolute asymmetry was defined (>15%). The only significant side-to-side difference was for right/left DFA α (p = 0.00; d = 1.12). Maximum absolute asymmetries were (right/left, dominant/nondominant): CV 18.2%, 18.0%; ApEn 34.5%, 32.3%; DFA α 4.9%, 5.0%. Different side-to-side comparisons yield different findings. Consideration for how side-to-side comparisons are performed (right/left, dominant/nondominant) is required. Because a significant difference existed for complexity but not variability, this indicates that both complexity-based and magnitude-based measures should be used when studying knee muscle force control.

Evidence for isokinetic and functional testing in return to sport decisions following ACL surgery

The rupture and reconstruction of the anterior cruciate ligament (ACL) of the knee are associated with an increased risk of functional instability, a reduction in sports performance, and a higher risk of future additional injuries. Competitive athletes who participate in sports that require pivoting, cutting, and jumping are at particularly high risk for ACL rupture. The return to sport progression continuum after surgery includes sports-specific rehabilitation, evaluation of strength and function, gradual participation in exercise training with progressively challenging activities in the field of play, participation in sports at a lower level, and finally a return to preinjury-level sports competition. This narrative review evaluates the evidence that supports the use of quadriceps and hamstrings isokinetic strength testing and sports-specific functional skills assessments to evaluate progress with rehabilitation after ACL surgery. Strength evaluations, hop tests, agility tests, and the limb symmetry index are described, as well as the associations of quadriceps and hamstrings muscle strength and functional test results with successful return to sports and the risk of ACL graft rupture and contralateral knee injuries. Suggestions for future research directions are presented including the importance of presurgery testing, standardization of test batteries, and comparison of test results with normative data.

Comparisons of Gait Variability and Symmetry in Healthy Runners, Runners with a History of Lower Limb Injuries, and Runners with a Current Lower Limb Injury

Background: Running is a cyclic movement requiring bilateral symmetry between the lower limbs to reduce injury risk. The assessment of side-to-side differences is often performed to detect functional deficits. Objectives: The purpose was to study side-to-side differences using clinical and running performance assessments in healthy runners (HR), runners with a history of lower limb injuries (RHI), and runners with a current lower limb injury (RLI). Methods: Forty-three runners were recruited, with 14 participants being allocated to the HR group, 13 to the RHI group, and 16 to the RLI group. Peak vertical ground reaction force (GRF), midfoot pressure, foot rotation, and gait variability were recorded using a Zebris FDM-T treadmill analysis system. Participants were also assessed using the navicular drop test. Dependent t-tests were used to determine if any differences existed between the lower limbs within each group. One-way ANOVAs were then used to investigate the side-to-side differences between the three groups. Results: Significant differences were seen in navicular drop height between lower limbs within both the HR (P = 0.02) and RHI (P = 0.009) groups, and side-to-side differences in foot rotation were greatest in the RLI group (~34%) compared to both the RHI (~30.5%) and HR (~24%) groups. The lateral variability of the center of pressure was greatest in the RLI group (37.1 mm) compared to the RHI (28.9 mm) and HR (22.2 mm) groups. Conclusions: Variability of butterfly center of pressure diagram may help identify runners at a greater risk of lower limb injury. Side-to-side differences should be expected to progressively decrease from the injured stage, through the recovery and return to sport phases. Target goals of less than 34% side-to-side difference for foot rotation and 37.1 mm for the lateral center of pressure variability may be used to help the decision-making process when considering a return to running practice.

Preseason weight-bearing ankle dorsiflexion in male professional football players with and without a history of severe ankle injury: A novel analysis in an English Premier League club

OBJECTIVES

Ankle injuries are common in professional football and have profound player/team/club consequences. The weight-bearing lunge-test (WBLT) assesses ankle dorsiflexion range-of-motion in football primary/secondary injury prevention and performance contexts. Data for uninjured and previously ankle-injured players in the English Premier League (EPL) is not available. This study analysed WBLT measurements (cm) within and between uninjured and previously severe ankle-injured players (injured-stiff group, injured-lax group) in one EPL club.

DESIGN

Cross-sectional.

SETTING

Preseason.

PARTICIPANTS

Forty-nine players (age 22.9 ± 4.6 yr; height 181.6 ± 5.2 cm; mass 77.7 ± 7.6 kg).

MAIN OUTCOME MEASURES

Prevalence (%) of previous unilateral severe ankle injury (USAI). Side-to-side (right/left, dominant/nondominant, injured/uninjured) WBLT comparisons at group-level (t-test [within-group]; Welch's ANOVA [between-group]; effect sizes [within-/between-group]) and individual-level (limb symmetry index [%]; absolute-asymmetry [%]).

RESULTS

Prevalence of USAI was 38.7%. There were no statistically-significant side-to-side differences for within-/between-group comparisons. Effect sizes: just-below-large (injured-stiff) and extremely-large (injured-lax) for within-group injured-side/uninjured-side comparisons; just-below-medium (injured-lax) to just-above-medium (injured-stiff) for injured-side comparisons to uninjured players. Absolute-asymmetries: uninjured players, 15.4±13.2%; injured-stiff, 21.8±33.6%; injured-lax 20.4±13.6%.

CONCLUSIONS

Over one-third of players had previous USAI. Effect sizes indicate substantial within-group side-to-side differences and less substantial between-group differences. Across groups, some players had absolute-asymmetries that may elicit concern in ankle primary/secondary injury prevention and performance contexts.

Development of a modified cross-over hop test to reduce measurement errors in return-to-competition testing

CONTEXT

 Hop tests play an important role in the rehabilitation process after injuries. A comparison of the jumping distances of both extremities allows for an evaluation of the injured limb. In the conventional cross-over hop test for distance, the jump width (medial vs. lateral) that the athlete has to cross during the jump is not standardised and therefore highly variable. This affects the absolute jump length in each jump series.

HYPOTHESIS

 Modifying the test may reduce the jump length variance between test series of an athlete as well as the test-dependent variations in the cross-over hop for distance.

METHODS

 N = 47 athletes from the German and French national Judo youth teams were included in the study (age: 15.3 years ± 13-17). A modified version of the cross-over hop for distance was developed with a cross-over width of 50 cm and a fixed landing zone of 10 cm. The jump lengths of the conventional test and the modified test were documented. The change in jump length variations of the two sexes were compared.

RESULTS

 The mean value of the coefficient of variation decreased significantly from 4.09 % to 2.83 % (p < 0.01) due to the test modification. This resulted in an absolute improvement in accuracy of 1.26 % and a relative improvement of 30.8 %. A comparison of the limb symmetry index between the conventional and the modified cross-over hop for distance revealed no significant differences.

CONCLUSION

 The modified cross-over hop for distance showed a significantly lower variation in jump lengths compared with the conventional cross-over hop for distance. As a result, more accurate statements can be made regarding the patient's return-to-competition progress.

Relationship Between 3 Single-Leg Functional Performance Tests for Netball Noncontact Knee Injury Prevention Screening in Uninjured Female Adult Players

CONTEXT

Single- versus double-leg landing events occur the majority of the time in a netball match. Landings are involved in large proportions of netball noncontact knee injury events. Of all landing-induced anterior cruciate ligament injuries, most occur during single-leg landings. Knowledge of whether different single-leg functional performance tests capture the same or different aspects of lower-limb motor performance will therefore inform clinicians' reasoning processes and assist in netball noncontact knee injury prevention screening.

OBJECTIVE

To determine the correlation between the triple hop for distance (THD), single hop for distance (SHD), and vertical hop (VH) for the right and left lower limbs in adult female netball players.

DESIGN

Cross-sectional.

SETTING

Local community netball club.

PARTICIPANTS

A total of 23 players (age 28.7 [6.2] y; height 171.6 [7.0] cm; mass 68.2 [9.8] kg).

INTERVENTIONS

There were 3 measured trials (right and left) for THD, SHD, and VH, respectively.

MAIN OUTCOME MEASURES

Mean hop distance (percentage of leg length [%LL]), Pearson intertest correlation (r), and coefficient of determination (r2).

RESULTS

Values (right and left; mean [SD]) were as follows: THD, 508.5 (71.8) %LL and 510.9 (56.7) %LL; SHD, 183.4 (24.6) %LL and 183.0 (21.5) %LL; and VH, 21.3 (5.2) %LL and 20.6 (5.0) %LL. All correlations were significant (P ≤ .05), r/r2 values (right and left) were THD-SHD, .91/.83 and .87/.76; THD-VH, .59/.35 and .51/.26; and SHD-VH, .50/.25 and .37/.17. A very large proportion of variance (76%-83%) was shared between the THD and SHD. A small proportion of variance was shared between the THD and VH (25%-35%) and SHD and VH (17%-25%).

CONCLUSION

The THD and SHD capture highly similar aspects of lower-limb motor performance. In contrast, the VH captures aspects of lower-limb motor performance different to the THD or SHD. Either the THD or the SHD can be chosen for use within netball knee injury prevention screening protocols according to which is reasoned as most appropriate at a specific point in time. The VH, however, should be employed consistently alongside rather than in place of the THD or SHD.

Hop Performance After Return to Sport in Anterior Cruciate Ligament-Reconstructed Gaelic Football and Hurling Athletes

PURPOSE

Anterior cruciate ligament (ACL) injuries are among the most severe injuries in the Gaelic Athletic Association. Hop tests measure functional performance after ACL reconstruction as they replicate the key requirements for a match situation. However, research examining functional recovery of ACL-reconstructed Gaelic athletes is lacking. The objective of this study is to determine if athletes restore normal hop symmetry after ACL reconstruction and to examine if bilateral deficiencies persist in hop performance following return to sport.

METHODS

A cross-sectional design was used to evaluate hop performance of 30 ACL-reconstructed Gaelic athletes who had returned to competition and 30 uninjured controls in a battery of hop tests including a single, 6-m, triple, and triple-crossover hop test.

RESULTS

In each test, the mean symmetry score of the ACL reconstruction group was above the cutoff for normal performance of 90% adopted by this study (98%, 99%, 97%, and 99% for the single, 6-m, triple, and triple-crossover hop, respectively). No significant differences in absolute hop scores emerged between involved and control limbs, with the exception of the single-hop test where healthy dominant limbs hopped significantly further than ACL-reconstructed dominant limbs (P = .02). No significant deficits were identified on the noninvolved side.

CONCLUSIONS

The majority of ACL-reconstructed Gaelic athletes demonstrate normal levels of hop symmetry after returning to competition. Suboptimal hop performance can persist on the involved side compared with control limbs. Targeted rehabilitation may be warranted after returning to competition to restore performance to levels of healthy uninjured athletes.

Practicability of lower extremity functional performance tests and their measurement properties in elite athletes: protocol for a systematic review

INTRODUCTION

Lower extremity injury (LEI) is highly prevalent and its occurrence increases the risk of future injury in athletic populations. Identifying athletes at risk of injury is the key to target injury-prevention programmes. Functional performance tests (FPT) assess an athlete's ability to produce and accept forces during movement tasks reflective of those experienced in sport, and are used to identify deficits in physical qualities or neuromuscular control. This review aims to identify FPT which have potential to predict LEI and assess their measurement properties associated with reliability, validity, responsiveness and practicability (interpretability and feasibility).

METHODS/ANALYSIS

This protocol will be reported using the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol and the COnsensus-based Standards for the selection of health Measurement INstruments Methodology. The search strategy has two stages: stage 1 will identify lower limb FPT used in athletic populations; and stage 2 will assess the measurement properties of the identified FPT. A sensitive search strategy will use MEDLINE, EMBASE, CINHAL and SPORTdiscus databases; from inception to June 2020. Hand searching reference lists, key journals and grey literature will be completed. One reviewer will complete search 1 and data extraction. Two reviewers will complete the search, data extraction and risk-of-bias assessment for search 2. Evidence will be pooled or summarised by individual measurement property by each individual study and grouped by FPT. Meta-analysis using a random effects model with subgroup analysis will be performed where possible. Pooled or summarised results for each FPT in relation to each measurement property will be rated against the criteria for good measurement properties. Two reviewers will assess the overall body of evidence per measurement property per FPT using the modified Grading of Recommendations, Assessment, Development and Evaluation guidelines. This review will enable clinicians to make an informed choice when selecting FPT.

ETHICS AND DISSEMINATION

No ethical approval is required for this review and the results will be disseminated through peer-reviewed publications and submitted for conference presentation.

PROSPERO REGISTRATION NUMBER

CRD42020188932.

Patellofemoral joint loading during the forward and backward lunge

OBJECTIVE

To examine patellofemoral joint (PFJ) loading in two lunge movements: Forward Lunge (FL) and Backward Lunge (BL).

DESIGN

Repeated Measures.

SETTING

University Biomechanics Laboratory.

PARTICIPANTS

20 asymptomatic females.

MAIN OUTCOME MEASURES

Six trials of two lunge movements (FL and BL) to a depth of 75% of leg length were performed. 3-D motion capture and force platforms were used to collect data as input into a musculoskeletal model to determine quadriceps force, PFJ reaction force, PFJ stress, and knee flexion angle.

RESULTS

Multivariate analysis indicated differences in PFJ loading variables and joint angles between the lunge movements (Forward vs. Backward) and phases (Down vs. Up). Quadriceps force, PFJ reaction force, and knee flexion angle were larger in the FL movement and Up phases. PFJ loading rate was greater in the FL movement along with a lower forward trunk tilt.

CONCLUSION

The FL produced greater PFJ loading variables compared to the BL. Further research is needed to examine a population of individuals who have patellofemoral pain (PFP) to see if their symptoms may be reduced when using the BL.

Electromyographic responses of knee isokinetic and single-leg hop tests in athletes :dominant vs. non-dominant sides

The purpose of the study is to perform the electromyographic (EMG) analysis of isokinetic and single-leg hop tests (SLHTs). We included 20 healthy male athletes (age: 23.18 years, height: 178.82 cm, weight: 73.76 kg and BMI: 47 kg/m²) voluntarily. Isokinetic knee strength tests at at 60°sec^-1, 180°sec^-1, 240°sec^-1 velocities and different SLHTs; Single leg (SL), Triple leg (THD) and Crossover (CHD) hop for distance tests, 6 m timed-hop test (6 m THT), Single leg vertical jump test (VJ) were measured. Muscle activations of quadriceps (Q); vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF) and hamstring (H); biceps femoris (BF) were obtained. There were significant differences in SL, THD, CHD and VJ in DS (p < 0.05).VJ revealed a statistical significance in NDS (p = 0.003). The comparison of the activations produced by the same muscles in different tests showed statistically significant differences in all the muscles for both sides (p < 0.05). In conclusion, we determined that the muscles produce similar activations in the isokinetic tests for both the DS and NDS, whereas there are differences in some of the SLHTs. The most active muscles were VM and RF (medial muscles) in isokinetic tests, and VL (lateral muscle) in SLHTs.g.

Evolution of Functional Recovery using Hop Test Assessment after ACL Reconstruction

The purpose of this study was to evaluate improvements in functional performance through the use of the Limb Symmetry Index of Single and Triple Hop tests between 12 and 52 weeks after anterior cruciate ligament reconstruction, and to compare these values with usual time-based and performance-based criteria used during the return to sport continuum. Repeated functional assessments using Single and Triple Hop Tests at 12, 16, 22, 26, 39 and 52 postoperative weeks were evaluated. At each session, the median and interquartile range of Limb Symmetry Index of tests were calculated and compared with the usual criteria: return to participation:≥85%, between 12-16 w; return to play:≥90%, between 26-39 w. The results indicate that the median increased over time to 39 postoperative weeks and then stabilized. For Single Hop Test, wide variability was seen at 12 and 16 weeks (interquartile range=20%); this was lower from 22 to 52 weeks (interquartile range=8-6%). At 12 weeks for Single Hop Test, the median was 83.6% and did not meet>85% criteria for return to participation. Hop tests could be interesting functional tests to follow the functional recovery and help decision-making regarding return to participation and return to play.

Greater knee flexion excursion/moment in hopping is associated with better knee function following anterior cruciate ligament reconstruction

PURPOSE

Individuals with impaired knee function after anterior cruciate ligament reconstruction (ACLR) may be at greater risk of developing knee osteoarthritis related to abnormal knee joint movement and loading. The aim of this study was to assess the association between knee biomechanics and knee laxity during hopping and clinically assessed knee function (i.e., patient-reported knee function and hop tests) following ACLR.

METHODS

Sixty-six participants (23 women, mean age 28 ± 6 years, mean 18 ± 3 months following ACLR) completed a standardized single-leg hopping task. Three-dimensional movement analysis was used to assess knee flexion excursion and body weight/height normalized knee flexion moments during landing for the involved limb. Anterior-posterior knee laxity was assessed with a KT-1000 knee arthrometer. Participants then completed a patient-reported knee function questionnaire and three separate hop tests (% of uninvolved limb) and were divided into poor and satisfactory knee function groups (satisfactory: ≥85% patient-reported knee function and ≥ 85% hop test symmetry). Associations between knee function and hop biomechanics/knee laxity were assessed using logistic regression and interquartile range scaled odds ratios (OR^IQR).

RESULTS

Greater knee flexion excursion (OR^IQR 2.9, 95%CI 1.1-7.8), greater knee flexion moment (OR^IQR 4.9, 95%CI 1.6-14.3) and lesser knee laxity (OR^IQR 4.7, 95%CI 1.5-14.9) were significantly associated with greater odds of having satisfactory knee function (≥ 85% patient-reported knee function and ≥ 85% hop test symmetry).

CONCLUSION

Greater knee flexion excursion/moment during hop-landing and lesser knee laxity is associated with better patient-reported knee function and single-leg hop test performance following ACLR. Patients with lower levels of knee function following ACLR demonstrated hop-landing biomechanics previously associated with early patellofemoral osteoarthritis. Therefore, interventions aimed at improving hop landing biomechanics in people with poor knee function are likely required.

LEVEL OF EVIDENCE

III, Cross-sectional study.

Functional Performance Measures Used for Return-to-Sport Criteria in Youth Following Lower-Extremity Injury

CONTEXT

As sport participation increases globally, so will injury-related risks. The process used to determine return-to-sport following injury is vital to future sport participation and injury prevention. Early specialization along with poor management of sport participation causes an increase in injury risk and potential long-term health consequences for youth athletes.

OBJECTIVES

Previous injury is a common intrinsic risk factor for new injuries. Identifying functional performance deficits, defined by return-to-sport criteria, minimizes these risk factors and provides athletes with guidelines to return safely to sport. The purposes of this clinical commentary and literature review are to provide a summary of current concepts and clinical practices and to identify functional performance measures as clinical assessment tools for return-to-play criteria in the youth population.

EVIDENCE

A literature review was completed using numerous databases, where 154 relevant articles were reviewed and 22 articles were included in this commentary. Of the 22 articles using functional performance measures for return-to-sport criteria, 6 were specific to youth, 12 had mixed populations of adults and youth, and 4 were normative samples for specific youth populations. Acquisition: The gaps in the literature pertaining to functional performance measures in the youth population are addressed, and future research needs for return-to-sport criteria are identified.

EVIDENCE SYNTHESIS

This descriptive literature review identifies 22 articles that meet the search criteria for the youth population discussing the use of clinical functional performance measures in order to identify return-to-sport criteria for lower-extremity injuries.

CONCLUSIONS

Due to the inconsistencies in terminology, definitions, and standardization of clinical assessment tools, it seems necessary to create a comprehensive functional performance test battery for the lower extremity that can be used as return-to-sport criteria.

Partial Anterior Cruciate Ligament Ruptures: Advantages by Intraligament Autologous Conditioned Plasma Injection and Healing Response Technique-Midterm Outcome Evaluation

The historical treatment options for partial anterior cruciate ligament (ACL) ruptures were conservative therapy or ACL reconstruction by injured bundle or entire ACL replacement. In awareness of the regenerative potential of biologic agents such as mesenchymal stem cells or platelet rich plasma (PRP), the healing response technique was developed to preserve the injured ACL with better outcomes than the conservative therapy. Further improvement of this technique seems to be obtained by the additional application of PRP products. Thus, the aim of this study was to evaluate the midterm outcome after intraligament autologous conditioned plasma (ACP) by a clinical, scoring, and functional performance assessment. 42 patients were evaluated in this study. The failure rate was 9.5%. Outcome evaluation showed good to excellent results. The scores were IKDC subjective 83.2 (SD 14.5), Lysholm 85.5 (SD 15.5), Tegner 4.7 (SD 1.7), and Cincinnati 85.4 (SD 15.5) after a mean follow-up of 33 months. Clinical examination showed stable Lachman test, negative pivot shift phenomenon, and a significant reduction in AP-laxity compared to preoperative status (rolimeter preoperative: 1.9 (SD1.4); postoperative 0.6 (SD1.8), p=0.001) in all patients. Functional performance testing showed no significant differences between the injured and healthy side. Return to sport was achieved after a mean of 5.8 months (SD 3.6) in 71.1% of the included patients. In summary, this new treatment option revealed in midterm follow-up promising results to treat partial ACL lesions with a reduced need for conversion to ACL reconstruction and with a high percentage of return to preinjury sport activity.

Poor knee function after ACL reconstruction is associated with attenuated landing force and knee flexion moment during running

PURPOSE

Poor knee function after anterior cruciate ligament reconstruction (ACLR) may increase the risk of future knee symptoms and knee osteoarthritis via abnormal knee joint loading patterns, particularly during high-impact activity. This study aimed to assess the relationship between poor self-reported or clinically measured knee function and knee moments/vertical ground reaction force (vGRF) in individuals following ACLR.

METHODS

61 participants (mean 16.5 ± 3 months following ACLR, 23 women) completed a patient-reported knee function questionnaire and three hop tests (% of uninvolved limb). Participants were divided into satisfactory and poor knee function groups (poor < 85% patient-reported knee function and/or < 85% hop test symmetry). The knee biomechanics of both groups were assessed with three-dimensional motion analysis during the stance phase of overland running at self-selected speeds, and the association between knee function and knee moments was assessed using analysis of covariance with running speed as a covariate.

RESULTS

Participants with poor knee function (n = 30) ran with significantly smaller peak knee flexion moments (moderate effect size 0.7, p = 0.03) and significantly smaller peak vGRFs (large effect size 1.0, p = 0.002) compared to those with satisfactory knee function (n = 31). No significant differences were observed for knee adduction and knee external rotation moments or knee kinematics.

CONCLUSION

Individuals following ACLR with poor self-reported knee function and/or hop test performance demonstrate knee moments during running that may be associated with lower knee joint contact forces. These findings provide greater understanding of the relationship between knee biomechanics during running and clinical assessments of knee function.

LEVEL OF EVIDENCE

III. Cross-sectional study.

A critical analysis of limb symmetry indices of hop tests in athletes after anterior cruciate ligament reconstruction: A case control study

BACKGROUND

Hop tests are frequently used to determine return to sports (RTS) after anterior cruciate ligament reconstruction (ACLR). Given that bilateral deficits are present after ACLR, this may result in a falsely high limb symmetry index (LSI), since LSI is calculated as a ratio between the values of the limbs.

HYPOTHESIS

Athletes after ACLR would achieve LSI>90% for the hop test. Secondly, athletes after ACLR demonstrate decreased jump distance on the single hop for distance (SLH) and triple leg hop for distance (TLH) and decreased number of hops for the side hop (SH) for both involved and uninvolved limbs compared to normative data of sex, age and type of sports matched healthy athletes.

MATERIALS AND METHODS

Fifty-two patients (38 males mean age 23.9±3.5years; 14 females mean age 21.7±3.5 years) who had undergone an ACLR participated in this study. Patients performed the 3 hop tests at a mean time of 7 months after ACLR. Hop distance, number of side hops and LSI were compared with normative data of 188 healthy athletes.

RESULTS

The differences between the involved limb and the uninvolved limb were significant in all hop tests (SLH P=0.003, TLH P=0.003, SH P=0.018). For females, only significant between limb differences were found in the SLH (P=0.049). For both the SLH and the TLH, significant differences were found between the involved limb and the normative data (males; SLH P<0.001, TLH P<0.001; females; SLH P<0.001, TLH P=0.006) and between the uninvolved limb and the normative data for both males and females (males; SLH P<0.001, TLH P<0.001; females; SLH P=0.003, TLH P=0.038). For the SH, only significant differences were found between the involved limb and the normative values in males (P=0.033).

CONCLUSION

Athletes who have undergone an ACLR demonstrate bilateral deficits on hop tests in comparison to age and sex matched normative data of healthy controls. Using the LSI may underestimate performance deficits and should therefore be analyzed with caution when used as a criterion for RTS after ACLR.

LEVEL OF EVIDENCE

III, case control study.

Criteria for Return to Sport after Anterior Cruciate Ligament reconstruction with lower reinjury risk (CR'STAL study): protocol for a prospective observational study in France

INTRODUCTION

The decision regarding when to return to sport after an anterior cruciate ligament reconstruction (ACLR) is an important one. Using a variety of subjective and objective parameters, various attempts have been made to determine an optimal timeline for a return to sport after ACLR, but none have been validated.The aim of the present study is therefore to determine which criteria or combination of criteria could allow to return to sport with the lowest possible risk of reinjury.

METHODS AND ANALYSIS

This study is a prospective cohort, single-centre study, with repeated assessments at 6, 9 and 12 months post-ACL surgical reconstruction and including a 3-year follow-up of patients' sporting activity and reinjuries. 275 patients will be included to test explanatory variables. Postural control analysis, knee laxity, questionnaires (International Knee Documentation Committee (IKDC), Tampa Scale of Kinesiophobia-11 (TSK-11), Anterior Cruciate Ligament-Return to Sport After Reinjury (ACL-RSI) and Single Assessment Numeric Evaluation (SANE)), modified Star Excursion Balance Test, running and sprinting biomechanics, Hop Tests and Isokinetic Tests will all be used. The primary outcome will be any reinjury during the follow-up period, defined as a graft rupture, a contralateral ACL rupture or any injury necessitating an interruption of training and requiring a medical consultation. Two groups will be constituted during the follow-up, separating reinjured from non-reinjured patients. In addition, classic analysis and data mining approaches will be used to build predictive models.

ETHICS AND DISSEMINATION

The results of this study will be disseminated through peer-reviewed publications and scientific presentations. Ethical approval was obtained through the ethics committee of the University Hospital of Saint-Etienne (reference number IRBN522015/CHUSTE).

The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee

PURPOSE

To investigate the effect of different loads of knee extensor open kinetic chain resistance training on anterior knee laxity and function in the ACL-injured (ACLI) knee.

METHODS

Fifty-eight ACLI subjects were randomised to one of three (12-week duration) training groups. The STAND group trained according to a standardised rehabilitation protocol. Subjects in the LOW and HIGH group trained as did the STAND group but with the addition of seated knee extensor open kinetic chain resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Anterior knee laxity and measurements of physical and subjective function were performed at baseline, 6 and 12 weeks. Thirty-six subjects were tested at both baseline and 12 weeks (STAND n = 13, LOW n = 11, HIGH n = 12).

RESULTS

The LOW group demonstrated a reduction in 133 N anterior knee laxity between baseline and 12 weeks testing when compared to the HIGH and the STAND groups (p = 0.009). Specifically, the trained-untrained knee laxity decreased an average of approximately 5 mm in the LOW group while remaining the same in the other two groups.

CONCLUSION

Twelve weeks of knee extensor open kinetic chain resistance training at loads of 2 sets of 20RM led to a reduction in anterior knee laxity in the ACLI knee. This reduction in laxity does not appear to offer any significant short-term functional advantages when compared to a standard rehabilitation protocol. These results indicate that knee laxity can be decreased with resistance training of the thigh muscles.

LEVEL OF EVIDENCE

Randomised controlled trial, Level II.

Contralateral limb deficit seven months after ACL-reconstruction: an analysis of single-leg hop tests

BACKGROUND

Following ACL-reconstruction, the non-injured leg (NIL) is used as a reference to assess injured leg (IL) recovery. However, deficits have been reported in the NIL questioning its use as a reference. The aim of this study is to assess whether NIL deficits are present while jumping after ACL-reconstruction.

METHODS

Thirteen males who had undergone ACL-reconstruction and 16 healthy subjects took part in the experiment. Jumping performance was assessed during a single and a triple hop for distance. Jumping performance, kinematic and kinetic data were recorded during single leg squat jumps. Values for both the NIL and the IL were compared to those of a control group (CG).

RESULTS

Jumping performance for single and triple hop for distance and single leg squat jump was lower in the NIL than in the CG (p=0.004, p=0.002, and p=0.016, respectively). During the squat jump, the knee joint was more extended and the ankle plantar-flexion was greater at take-off while the peak total moment was 15% lower in the NIL than in the CG (p=0.002, p=0.002, and p=0.009, respectively). We found consistent evolutions in the NIL and the IL compared to the CG for jumping performance, initial joint angles, and peak total moment during the squat jump, but the opposite was found for the ankle and knee joint angles at squat jump take-off.

CONCLUSIONS

Jumping strategies are impaired in the NIL after ACL-R during jump tasks with some deficits matching those observed in the IL and some specific to the NIL.

LEVEL OF EVIDENCE

III, Case control study.

A Unique Rectus Femoris Injury in an Adolescent Professional Soccer Player: A Case Report

CASE

A sixteen-year-old professional soccer player presented with persistent pain in the right thigh of two years' duration and the inability to return to play. Evaluation revealed a chronic rupture of the rectus femoris muscle. Because physiotherapy and rehabilitation failed to help, a surgical repair was performed. He returned to his previous activity level within nine months after surgery.

CONCLUSION

Rupture of the proximal part of the rectus femoris should be acknowledged in the differential diagnosis, especially when presenting with persistent pain in the anterior aspect of the thigh lasting more than one year. Delayed repair might be recognized as a reasonable option for chronic rupture of the proximal part of the rectus femoris.

Functional Performance Testing and Patient Reported Outcomes following ACL Reconstruction: A Systematic Scoping Review

Objective. A systematic scoping review of the literature to identify functional performance tests and patient reported outcomes for patients who undergo anterior cruciate ligament (ACL) reconstruction and rehabilitation that are used in clinical practice and research during the last decade. Methods. A literature search was conducted. Electronic databases used included Medline, PubMed, Cochrane Library, EMBASE, CINAHL, SPORTDiscus, PEDro, and AMED. The inclusion criteria were English language, publication between April 2004 and April 2014, and primary ACL reconstruction with objective and/or subjective outcomes used. Two authors screened the selected papers for title, abstract, and full-text in accordance with predefined inclusion and exclusion criteria. The methodological quality of all papers was assessed by a checklist of the Critical Appraisal Skills Programme (CASP). Results. A total of 16 papers were included with full-text. Different authors used different study designs for functional performance testing which led to different outcomes that could not be compared. All papers used a measurement for quantity of functional performance except one study which used both quantity and quality outcomes. Several functional performance tests and patient reported outcomes were identified in this review. Conclusion. No extensive research has been carried out over the past 10 years to measure the quality of functional performance testing and control stability of patients following ACL reconstruction. However this study found that the measurement of functional performance following ACL reconstruction consisting of a one-leg hop for a set distance or a combination of different hops using limb symmetry index (LSI) was a main outcome parameter of several studies. A more extensive series of tests is suggested to measure both the quantitative and qualitative aspects of functional performance after the ACL reconstruction. The KOOS and the IKDC questionnaires are both measures that are increasingly being used for ACL reconstruction throughout the last decade.

Measures of functional performance and their association with hip and thigh strength

CONTEXT

Insufficient hip and thigh strength may increase an athlete's susceptibility to injury. However, screening for strength deficits using isometric and isokinetic instrumentation may not be practical in all clinical scenarios.

OBJECTIVE

To determine if functional performance tests are valid indicators of hip and thigh strength.

DESIGN

Descriptive laboratory study.

SETTING

Research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Sixty-two recreationally athletic men (n = 30, age = 21.07 years, height = 173.84 cm, mass = 81.47 kg) and women (n = 32, age = 21.03 years, height = 168.77 cm, mass = 68.22 kg) participants were recruited.

INTERVENTION(S)

During session 1, we measured isometric peak force and rate of force development for 8 lower extremity muscle groups, followed by an isometric endurance test. During session 2, participants performed functional performance tests.

MAIN OUTCOME MEASURE(S)

Peak force, rate of force development, fatigue index, hop distance (or height), work (joules), and number of hops performed during the 30-second lateral-hop test were assessed. The r values were squared to calculate r (2). We used Pearson correlations to evaluate the associations between functional performance and strength.

RESULTS

In men, the strongest relationship was observed between triple-hop work and hip-adductor peak force (r(2) = 50, P ≤ .001). Triple-hop work also was related to hip-adductor (r(2) = 38, P ≤ .01) and hip-flexor (r(2) = 37, P ≤ .01) rate of force development. For women, the strongest relationships were between single-legged vertical-jump work and knee-flexor peak force (r(2) = 0.44, P ≤ .01) and single-legged vertical-jump height and knee-flexor peak force (r(2) = 0.42, P ≤ .01). Single-legged vertical-jump height also was related to knee-flexor rate of force development (r(2) = 0.49, P ≤ .001). The 30-second lateral-hop test did not account for a significant portion of the variance in strength endurance.

CONCLUSIONS

Hop tests alone did not provide clinicians with enough information to make evidence-based decisions about lower extremity strength in isolated muscle groups.

Analysis of lower limb asymmetries by isokinetic and vertical jump tests in soccer players

Assessment of lower extremity bilateral asymmetries in soccer players is important for both injury prevention and performance. The purpose of this investigation was to compare isokinetic knee extensor assessment of asymmetry with a more specific countermovement jump (CMJ). Forty-six Brazilian male professional soccer players participated in this study. The maximal power, maximal force and impulse were determined during CMJ and the total work and peak torque at 60, 180, and 300°·s during isokinetic leg extension, separately for each leg. Factor analysis was performed for all investigated variables, and the diagnostic concordance between different criteria was analyzed by McNemar's χ test. The factor analysis showed that the isokinetic and CMJ tests were widely independent methods for the assessment of bilateral differences. Concordance of the diagnostic information could only be found between the maximal force during CMJ and the total work and peak torque at 180 and 300°·s during isokinetic leg extension. Impulse and maximal power during CMJ on a double force platform appear to be appropriate additional variables for the identification of bilateral differences. Therefore, it might be pertinent to perform, in addition to isokinetic assessment, a vertical jump test on a force platform to assure widespread and reliable diagnostic information.

Psychological responses matter in returning to preinjury level of sport after anterior cruciate ligament reconstruction surgery

BACKGROUND

Up to two-thirds of athletes may not return to their preinjury level of sport by 12 months after anterior cruciate ligament (ACL) reconstruction surgery, despite being physically recovered. This has led to questions about what other factors may influence return to sport.

PURPOSE

To determine whether psychological factors predicted return to preinjury level of sport by 12 months after ACL reconstruction surgery.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

Recreational and competitive-level athletes seen at a private orthopaedic clinic with an ACL injury were consecutively recruited. The primary outcome was return to the preinjury level of sports participation. The psychological factors evaluated were psychological readiness to return to sport, fear of reinjury, mood, emotions, sport locus of control, and recovery expectations. Participants were followed up preoperatively and at 4 and 12 months postoperatively.

RESULTS

In total, 187 athletes participated. At 12 months, 56 athletes (31%) had returned to their preinjury level of sports participation. Significant independent contributions to returning to the preinjury level by 12 months after surgery were made by psychological readiness to return to sport, fear of reinjury, sport locus of control, and the athlete's estimate of the number of months it would take to return to sport, as measured preoperatively (χ(2) 2 = 18.3, P < .001, classification accuracy = 70%) and at 4 months postoperatively (χ(2) 4 = 38.7, P < .001, classification accuracy = 86%).

CONCLUSION

Psychological responses before surgery and in early recovery were associated with returning to preinjury level of sport at 12 months, suggesting that attention to psychological recovery in addition to physical recovery after ACL injury and reconstruction surgery may be warranted. Clinical screening for maladaptive psychological responses in athletes before and soon after surgery may help clinicians identify athletes at risk of not returning to their preinjury level of sport by 12 months.

The effects of a prophylactic knee brace and two neoprene knee sleeves on the performance of healthy athletes: a crossover randomized controlled trial

Knee injury is one of the major problems in sports medicine, and the use of prophylactic knee braces is an attempt to reduce the occurrence and/or severity of injuries to the knee joint ligament(s) without inhibiting knee mobility. The aim of the present study was to examine the effect of one recently designed prophylactic knee brace and two neoprene knee sleeves upon performance of healthy athletes. Thirty-one healthy male athletes (age = 21.2 ± 1.5) volunteered as participants to examine the effect of prophylactic knee brace/sleeves on performance using isokinetic and functional tests. All subjects were tested in four conditions in a random order: 1. nonbraced (control) 2. using a neoprene knee sleeve 3. using a knee sleeve with four bilateral metal supports and 4. using a prophylactic knee brace. The study design was a crossover, randomized, controlled trial. Subjects completed single leg vertical jump, cross-over hop, and the isokinetic knee flexion and extension (at 60, 180, 300°/sec). Data were collected from the above tests and analyzed for jump height, cross-over hop distance, peak torque to body weight ratio and average power, respectively. Comparisons of these variables in the four testing conditions revealed no statistically significant difference (p>0.05). The selected prophylactic brace/sleeves did not significantly inhibit athletic performance which might verify that their structure and design have caused no complication in the normal function of the knee joint. Moreover, it could be speculated that, if the brace or the sleeves had any limiting effect, our young healthy athletic subjects were well able to generate a mean peak torque large enough to overcome this possible restriction. Further studies are suggested to investigate the long term effect of these prophylactic knee brace and sleeves as well as their possible effect on the adjacent joints to the knee.

Bilateral and gender differences during single-legged vertical jump performance in healthy teenagers

The determination of physiologic lower limb functional imbalance among healthy teenagers is important to follow the rehabilitation progress and return to normal activity of injured subjects. We investigated the differences in vertical jump capacity between both legs in a group of healthy boys and girls, considering the performances in the dominant vs. non-dominant, and in the most vs. least efficient leg. Strength and power performances were compared in 117 boys and 106 girls aged 10-16 years during a single-leg vertical countermovement jump (SLVCJ) test. When leg dominance was defined subjectively by the participant, no difference was noted between the 2 legs. Statistically significant differences were recorded between the most and less efficient leg in strength and power performances for both genders. Girls had significantly greater peak strength than did age-matched boys, but boys showed significant increases in maximal power outputs compared with that shown by age-matched girls. When the results were analyzed according to the percentage of participants falling within certain bands of limb asymmetry, approximately 20-30% showed a difference of >15% between the 2 limbs without any relation to gender. Subjective expression of leg dominance cannot be used as a predictor of SLVCJ performance. Differences of <15% in SLVCJ performance between both legs should be considered as the physiological norm in this age group. A greater appreciation of the potential diagnostic value of the SLVCJ test may be obtained if the results are interpreted in terms of the percentage of subjects falling within certain bands of limb asymmetry. Gender-based differences in the SLVCJ test vary and depend upon whether the results are interpreted in terms of strength or power output.